Method of making cupped shells



Oct. 13, 1953 o. H. MAY

METHOD OF MAKING CUPPED SHELLS 2 Sheets-Sheet 1 Filed June 28, 1950 Oct. 13, 1953 o. H. MAY

METHOD OF MAKING CUPPED SHELLS v 2 Sheets-Sheet 2 Filed June 28, 1950 INVENTORY OTro H- WA) Patented Oct. 13, 1953 UNITED STATES PATENT OFFICE 1 Claim. 1

This invention relates to a method of makin cupped shells, particularly those which are subsequently formed into long shells of various shapes, e. g. into cylinders as they are employed as storage facilities for compressed gas.

At present cylindrical shells are almost exclusively formed from round blanks which are first drawn into cupped shells and subsequently ironed or otherwise suitably worked. When cutting such blanks from sheets, plates or strips the scrap experienced is very high. It has been tried to reduce this scrap by cutting the blanks in staggered rows from the sheets or plates, yet the percentage of scrap is still considerable. Although it is possible to cut multi-sided blanks of various numbers of sides out of sheets, plates or strips without or practically without any scrap, such multi-sided blanks have the decided disadvantage that rather long ears corresponding to the number of sides are produced on the upper rim when these blanks are drawn into cupped shells. These ears are greatly enlarged during the subsequent redrawing operations and have to be cut off either after the cupping operation or later, with the result that the scrap avoided at the blanking operation is now experienced at a later stage of the process.

It is therefore the main object of this invention to reduce or practically eliminate the scrap when making cupped shells out of multi-sided blanks. As the round shape of blanks is best suited for drawing cylindrical shells, the invention relates to a method of cutting multi-sided blanks from sheets, plates or strips with substantially no scrap and to shape these blanks into those resembling the circular form to a higher degree than the original blanks.

In a preferred method of making cupped shells according to the invention an n-sided blank is first cut from a sheet, plate or strip, a being a whole number greater than 2, then shaped into a zn-sided blank of the same thickness and finally drawn into a cupped shell.

When drawing this cupped shell it is advantageous to change the thickness of the blank as little as possible.

The shaping of the n-sided blank into a 2n sided one can be done in various ways. A preferred method consists in forcing flat-faced members against the corners of the blank, the blank being held between fiat surfaces which prevent any change in thickness of said blank.

The ears generated during the cupping operation are in a preferred method flattened by means of a ring-shaped punch forced against the upper rim of the shell. It is thus possible to reduce the scrap experienced during the entire forming process practically to zero aside from a small scrap unavoidably produced when trimming the upper end of the shell.

In the accompanying drawings in which one of the various methods of making cupped shells according to the invention is represented:

Fig. 1 is a perspective view showing a square blank cut off from a metal strip;

Fig. 2 is a perspective view of a device for shaping the square into an octagon, with the jaws in their starting position;

Fig. 3 is a perspective view of the same device with the jaws in their extreme forward position;

Fig. 4 is a perspective view of the octagonal blank;

Fig. 5 is a perspective view of a device for fiattening the rim of the cupped shell;

Fig. 6 is a perspective View of the cupped shell before the flattening operation.

Fig. 7 is a perspective View of the cupped shell after the flattening operation.

In order to avoid circumlocution equal parts are given the same numerals throughout the various figures.

In Fig. l a square blank I is shown cut oli from the metal strip 2, the side of the square being equal to the width of the strip.

Referring to Fig. 2, the square blank i is placed between four jaws 3 having flat faces 3| of a width equal to the thickness of the blank. The jaws are yet in their initial position, the faces being arranged at an angle of 45 degrees with respect to the sides of the square. The jaws are operated by four toggle linkages having'toggle arms Aand operating links 5. Two toggle systems are left on" for claritys sake. The punch 6 shown in its upper position has a diameter greater than the diagonal of the square and serves to hold the blank on its bottom plate during the squeezing operation.

Referring to Fig. 3, the jaws 3 have moved into their extreme forward positions with the punch holding the blank I on its bottom plate. As in Fig. 2 only two toggle systems for actuating the jaws are shown for claritys sake, the toggle arms bein now straightened. The faces iii of the jaws 3 have moved underneath the punch 6 and in doing so have shaped the four-corner portions into fiat sides. The square blank shown in Fig. 3 is thus transformed into one of octagonal shape.

The octagonal blank 1 as it leaves the shaping device is shown in Fig. 4.

Referring to Fig. 5, the octagonal blank is now drawn into a cupped shell by forcing it through the drawing ring 8 by means of punch 9. Upon completion of this operation the shell remains inside the cylindrical extensions of the drawing ring, the cup resting on a pressure pad [0, which is fixed in position during the subsequent operation. With this pa-d held stationary, a ringshaped punch 12 descends on the rim of the cupped shell, thereby flattening the ears produced during the cupping operation. Illustrated on the left is the left half of the ring-shaped punch in its upper position, the shell showing distinct ears in the half shown underneath said punch, and illustrated on the right is the right half of the ring-shaped punch in its lower position, the flattening of the ears being now completed as shown by the fiat rim of the right part of the cupped shell.

Fig. 6 illustrates the cup ll after the cupping operation, with the rim showing 8 ears. Walls and bottom thickness are substantially equal as yet.

Fig. '7 shows the cupped shell 13 after the ears are flattened by ring-shaped punch II. This cup can now be readily redrawn and ironed, the scrap experienced during the subsequent operations being substantially confined to the scrap produced when trimming the upper rim of the shell in its final shape in the usual manner.

In view of the above, it will be seen that the object of the invention is achieved and other advantageous results attained.

As many changes can be made without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

A method of making cupped shells, comprising in combination, the steps of cutting in cold condition a polygonal blank having an even number of sides and corners, respectively; pressing said corners inwardly in diagonal direction for deforming said corners into straight sides in cold condition of said blank while retaining the top and bottom faces of said blank substantially parallel so as to form a reshaped blank having twice as many substantially equal sides, and corners, respectively, as said blank; drawing the thus obtained reshaped blank in cold condition into a cupped shell; and flattening the projecting ears formed by the corners of said reshaped blank on the edge of the thus formed cupped shell.

OTTO H. MAY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 348,079 Wellman Aug. 24, 1886 803,071 Schoen Oct. 31, 1905 834,761 Schoen Oct. 30, 1906 848,927 Schoen Apr. 2,1907 866,025 Hansen Sept. 17,1907 881,399 Hansen Mar. 10, 1908 1,368,725 Hooker Feb. 15, 1921 2,343,253 Clark Mar. 7, 1944 

